Google "cooperative definition" and you get:
a farm, business, or other organization which is owned and run jointly by its members, who share the profits or benefits.
Sounds exactly like what we have for electric power utilities around here.
I don't believe they have any government involvement in their operations other than to follow any laws that apply to them.
The municipal utilities that are around do have a city council that intervenes to some extent, but the utility itself still has it's own board members and their own meetings for conducting utility business and making budget decisions. Their actions often still must be submitted to city council and council has to approve those actions, but most of the time they do, they are basically like a separate department within the city government with their own supervisory board, just like the police, fire, rescue, parks and recreation department, water/sewer, etc.